The present invention relates to telemetry.
One application of telemetry is the collection of data from a metering system, which is a system that periodically measures one or more parameters at multiple locations. Utility companies meter, e.g., the amount of natural gas, electricity, and water consumed by households.
The collection of data from a metering system can be performed by physically inspecting of individual meters. For example, in residential areas, electrical utility companies use electromechanical meters with rotating disks to measure the consumption of electricity. Electrical utility companies send a person, sometimes referred to as a meter reader, to record the meter measurement about once a month. Metering of natural gas and water is performed similarly.
Alternatively, a metering system can have multiple sensors that transmit meter data, such as measured parameters, from multiple locations to multiple collection devices. There are usually fewer collection devices than sensors. Transmissions from a sensor to a collection device are used to collect meter data. The collection devices can be positioned such that transmissions from a single sensor are received by one or more one collection devices. In response to the transmissions received from multiple sensors, the multiple collection devices transmit data to a central monitoring station. The described telemetry eviscerates the need for a person such as a meter reader to manually record meter measurements.
Conventional telemetry systems often adopt a many-to-one approach to telemetry communications. Specifically, a conventional telemetry system consists of a plurality of telemetry units (“TU” or “TUs”), such as the described sensors, that send their data primarily to one data processing center, such as the described central monitoring station. At times, the data processing center needs to initiate communications to an individual telemetry unit or to all telemetry units in its system. For example, the central monitoring station may need to reset a sensor's demand register value in a certain electricity meter. Similarly, the central monitoring station may need to set or change a time-of-use configuration in all meters of a certain class. Or more generally, the processing center may need to recover data, such as load profile data or demand data, lost during previous communication attempts by a telemetry unit.
Conventional telemetry systems usually adopt a dumb-pipe approach to the initiation of communications with a telemetry unit or group of telemetry units by a data processing center. In such systems, software at the data processing center sends commands through the dumb pipe, directly to the telemetry units for processing. See, for example, the conventional system shown in FIG. 1. The telemetry units respond to the data processing center's commands with data and acknowledgements sent through the dumb pipe.